Abstract:
AbstractTemperate reptiles are often considered to be low-energy systems, with their discrete use of time and energy making them model systems for the study of time-energy budgets. However, the semifrequent replacement and sloughing of the epidermis is a ubiquitous feature of squamate reptiles that is often overlooked when accounting for time and energy budgets in these animals. We used open-flow respirometry to measure both the energetic effort of ecdysis and the duration of the associated metabolic upregulation (likely related to behavioral changes often reported for animals in shed) in wild-caught timber rattlesnakes (Crotalus horridus). We hypothesized that total effort of skin biosynthesis and physical removal would be related to body mass and expected the duration of the process to remain static across individuals at a fixed temperature (25°C). We provide both the first measurements of the cost of skin biosynthesis and physical removal in a reptile and the highest-resolution estimate of process duration recorded to date. We found that skin biosynthesis, but not the cost of physical removal of the epidermis, was related to body mass. Shed cycle duration was consistent across individuals, taking nearly 4 wk from process initiation to physical removal of the outermost epidermal layer. Total energetic effort of ecdysis was of sizeable magnitude, requiring ∼3% of the total annual energy budget of a timber rattlesnake. Energetic effort for a 500-g snake was equivalent to the amount of metabolizable energy acquired from the consumption of approximately two adult mice. Ecdysis is a significant part of the time-energy budgets of snakes, necessitating further attention in studies of reptilian energetics.
摘要:
温带爬行动物通常被认为是低能量系统,随着时间和能量的离散使用,它们为时间-能量预算的研究建立了模型。然而,表皮的半取代和脱落是鳞片状爬行动物的一个普遍存在的特征,在考虑这些动物的时间和能量预算时,它经常被忽略。我们使用开放流量呼吸测量法来测量野生捕获的木材响尾蛇(Crotalushordus)中蜕皮的能量和相关代谢上调的持续时间(可能与棚中动物经常报告的行为变化有关)。我们假设皮肤生物合成和物理去除的总努力与体重有关,并期望该过程的持续时间在固定温度(25°C)下在个体中保持静态。我们提供了对爬行动物中皮肤生物合成和物理去除成本的首次测量,以及迄今为止记录的过程持续时间的最高分辨率估计。我们发现皮肤生物合成,但不是物理去除表皮的成本,与体重有关。棚屋周期持续时间在个体之间是一致的,从过程开始到物理去除最外层表皮层,需要近4周。蜕皮的总精力相当大,需要木材响尾蛇年度总能源预算的3%。500克蛇的能量相当于从大约两只成年小鼠的消耗中获得的代谢能的量。Ecdysis是蛇的时间能量预算的重要组成部分,在爬行动物能量学的研究中需要进一步关注。